Subject: .deb signing key insecure against MitM

From: Thomas Mayer <[email-masked]>
Date: Mon, 7 Mar 2016 16:03:21 +0100

I just visited http://www.postgresql.org/download/linux/debian/ and my 
impression is that the way the signing key is published is not secured 
against wrong origin or manipulation by a man in the middle (MitM) attacker.

Meaning, that if a MitM attacker can compromise downloads, he or she is 
also able to compromise the documentation site including the source of 
the signing key, e.g. by publishing the attacker's signing key to the 
user. Debian's apt-get will not complain if everything fits together.

Therefore, I suggest that the whole page should be TLS secured 
(HTTPS-only), not because of encryption but to ensure origin and 
integrity of the signing key.

It is not sufficient to have the signing key itself TLS-secured, because 
the documented hyperlink

https://www.postgresql.org/media/keys/ACCC4CF8.asc

could easily be manipulated by the MitM as well.

I also suggest to go through the documentation to find similar occurences.

Last, but not least, people might also tend to copy-paste some bash 
commands which offers additional possibilities for MitM to let users 
install malicious software with root permissions. In the long-run, I 
suggest to go for a HTTPS-only strategy with PostgreSQL's documentation 
(all of it).

Related, but securing the download: 
http://www.postgresql.org/message-id/flat/[email-masked][email-masked]

Note that the apt repository (including the downloadable packages) does 
not have to be TLS-secured as long as the package signing mechanism 
works well. Still, the additional security might not be harmful for most 
users.

Best regards
Thomas Mayer

--
https://www.2bis10.de

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---

From: Magnus Hagander <[email-masked]>
Date: Mon, 7 Mar 2016 16:06:09 +0100

On Mon, Mar 7, 2016 at 4:03 PM, Thomas Mayer <[email-masked]>
wrote:

> also able to compromise the documentation site including the source of the
> signing key, e.g. by publishing the attacker's signing key to the user.
> Debian's apt-get will not complain if everything fits together.
>
> (HTTPS-only), not because of encryption but to ensure origin and integrity
> of the signing key.
>

Work is under way to make the entire website available under https only.
It's blocked behind some other work at this point, but once we get there,
it should make this situation a lot better.

-- 
 Magnus Hagander
 Me: http://www.hagander.net/
 Work: http://www.redpill-linpro.com/